Despite civil wars in Africa and the Mideast, ongoing strife in Afghanistan, and the barrage of local and national crimes reported on the nightly news, people are living in a much more peaceful era than they might think.

“During the thousands of years humans spent as hunter-gatherers, the average rate of violent death was higher than the worst years of World War II, and about five times higher than the rate of death from all wars, genocides, and human-made famines in the 20th century,” said Pinker, the Johnstone Family Professor of Psychology and Harvard College Professor.

“Believe it or not … today we may be living in the most peaceable era in our species’ existence,” wrote Pinker in his latest book, “The Better Angels of Our Nature: Why Violence Has Declined,” which takes its title from that age-old dichotomy: the devil on one shoulder, whispering temptation, enticing us to act on sinister urges, and the angel on the other shoulder, holding us back with caution and consequence.

“Human nature is extraordinarily complex, and includes both bellicose and peaceable motives. Outbreaks of violence or peace depend on which is more engaged in a given time and place,” said Pinker. “Among the better angels of our nature — the psychological faculties that caused violence to decline — are self-control, empathy, and a sense of fairness.”

But, Pinker added, “My most surprising discovery was that the most important better angel may be reason: the cognitive faculties with which we understand the physical and social world. It was an ironic discovery, given that cognition and language are my research specialty.”

What historical forces have been engaging these better angels? Pinker cites “the outsourcing of deterrence and revenge to a disinterested third party, including the police and court system; the growth of commerce, which replaces zero-sum plunder with positive-sum trade and reciprocity; the forces of cosmopolitanism, such as mobility and literacy, which encourage people to take other vantage points and hence consider their interests; and the growth of education, public discourse, science, and abstract reasoning, which discourage parochial tribalism and encourage people to treat violence as a problem to be solved rather than as a contest to be won.”

To put this all in context, Pinker shows that homicide rates in Europe have declined 30-fold since the Middle Ages. Human sacrifice, slavery, punitive torture, and mutilation have been abolished around the world. And, he said, “Great powers and developed countries have stopped going to war. And in the world as a whole, deaths in warfare may be at an all-time low.”

In his research, Pinker’s favorite discovery was learning that “every category of violence — from deaths in war to the spanking of children to the number of motion pictures in which animals were harmed — had declined.” That, he admitted, “makes the present less sinister, the past less innocent.”

He believes that “forms of institutionalized violence that can be eliminated by the stroke of a pen — such as capital punishment, the criminalization of homosexuality, the callous treatment of farm animals, and the corporal punishment of children in schools — will continue to decline, because decision-making elites will continue to be swept by the humanitarian tide that has carried them along for centuries.”

Pinker is now working with graduate student Kyle Thomas on a new project, studying “common knowledge,” the state where two people not only know something important, but each knows that the other knows that he knows it, ad infinitum.

“My next book project will be a style manual for the 21st century — a competitor to Strunk and White that will incorporate insights from modern linguistics and cognitive science,” he said.

“But ‘Better Angels’ made me appreciate the forces of civilization and enlightenment which have made our lives so much more peaceable than those of our ancestors: the police, a court system, democracy, education, literacy, commerce, science, the Enlightenment, and the forms of secular humanism that grew out of it — which are easy to take for granted.”

Targeting mechanisms in the central nervous system might yield the beneficial effects of low-calorie diets on healthy aging without the need to alter food intake, suggests new research from Harvard T.H. Chan School of Public Health.

Jose Gomez-Ibanez, a transportation and infrastructure policy expert at Harvard Kennedy School and the Harvard Graduate School of Design, talks about the political and financial hurdles to smoothly running public transit systems.

Harvard researchers at Massachusetts General Hospital find that participating in an eight-week mindfulness meditation program appears to make measurable changes in brain regions associated with memory, sense of self, empathy, and stress.

Published to commemorate Harvard’s 375th anniversary, “Explore Harvard,” a collection of contemporary and historical photographs, showcases the myriad intellectual exchanges that make the University a citadel of learning.